It is well known to provide water cooling for engines in railway cars. In some cases, the heat generated by the engine has been used for other purposes.
Because of the varying heating requirements of a railway car due to the wide variations of temperature conditions under which is operates, it is difficult to utilize the waste heat from an engine directly and continuously to provide conventional heating for the car. The reason for this is that there are times, during warm or mild temperature conditions, when little or no heat is required and other times, as during the winter months, when the heating requirements are high.